Sheet metal compressor casing



Jan. 17, 1961 I H. w. WELSH v 2,968,468

SHEET METAL COMPRESSOR CASING Filed'Augpl3, 1957 2 Sheets-Sheet 2 III ll I l f/IIIIIJII'IIIIIIIIIIIII w .24 m 11- if? #7 INVENTOR.

' in 241M 24 2m ATTORNEY Motors Corporation, Detroit, Mich., a corporation of Delaware 7 Filed Aug; 13, 1957, Set. N 677,934 4 Claims: (Cl. 253*78) This invention relates to turbo-machines and more particularly to sheet metal compressor casing structures.

In turbo-machines, especially those :used in aircraft installations, such as turb'o j'et and turbd-prop engines, it is essential that the weight of the-structure be kept to a minimum. However, due to the...wi'cle range of tem* peratures and stresses encountered in such installations it is also essential that the structiira'l elements have the strength and rigidity to resist theselextreme cond tions. In the past it has been common practice to utilize relatively thick forged casing members and structural components that require considerable machining during tabr ication and add substantial weight to the engine.

It would be advantageous to make an engine from sheet metal components which by proper design will provide a more rigid structure for a given weight, and need a minimum of machining eorn pa'red to a conventional forged and machined design.

Accordingly, it is an object of the invention to provide a turbo-machine struethre utilizing light weight sheet metal components. It is a further object at the inven tion to provide a compressor casingutilizing relatively thin sheet metal elements that provide a high rigidity, enable close control of critical dimensions, and require a minimum amount of machining tabric'ation.

Some preferred e'mbodirnentsof the invention are il lustr'ated in the accompanying drawings in which:

Fig. 1 is a partial longitudinal sectionof agas turbine compressor utilizing one of the referred a gernents; Fig. 2 is an enlarged view' showing theca stifiening and stator blade aligning and locating means of Fig, 1; Fig. 3 shows a modification of the arrangement of Figs. 1 and 2;

Fig. 4 shows another arrangement utilizing a shroud- Fig. 6 shows still another arrangement wherein the casing stiffeners form rotor shrouds.-

Referring to Figs. 1 and 2, 1 represents a sheet metal outer compressor casing which is connected byflanges at one end through suitable means, not shown, to a diffuser case 2 and which acts to enclose alternate rows of stator vanes 3 that are secured to the outer casing 1, and rows of compressor rotor blades 5 secured by known means to a rotor 7. The stator vanes 3 have reduced end portions 9 that extend through slots in a sheet metal ring 11 and through corresponding slots in sheet metal channel shaped semi annular ring 13 that is welded or otherwise secured to the inner ring 11. The stator vanes 3 may be secured to the retaining assembly 11-l3 by any suitable means such as by brazing or Welding. The channel member 13 is located within a larger channel shaped sheet metal ring 15 that is welded or otherwise secured to the outer casing 1. The channel ring 15 has circumferential beads 17 formed thereon that engage the channel ring 13 to prevent axial movement of the vane assembly relative to the casing 1. The channel rings 15 fur- Patented Jan. 1?, 1961 2. ther act to give the outer casing considerable rigidity and therefore act as stilfener rings.

The casing would normally be made in two semicircular halves and semi-circular stiffener rings 15'- welded thereto. After assembly of the two halves of the easing the inner diameter edges 18 of the stifiener rings are ground to provide the proper roundness or" the casing itself. This fabrication method permits reasonable out-of-round tolerances of the outer shell while maintaining the accuracy of the critical internal dimensions. After the two casing halves are fabricated, they are fastened together and held against rotation by any suitable means such as shown in my co-pending U.S. application S.N. 677,933, filed August 13, 1957,- direeted to Stator Ring Assembly. The outer stator ring 13 is machined or ground at 20 to mate with the inner'ground l means, for example, as by the method shown in Patent No. 2,772,069. m

An inner compressor casing member 19 provides additional strength and rigidity and at the same time acts as a shroud for the compressor rotor blades 5. The inner casing members 19 are secured to tabs 21 which are held between the inner ground edges. 18 of the stiffener rings 15 and the outer ground portions 22 of the stator ring 13. It will be seen that this arrangement shown in Figs. 1 and 2 provides a structure. that has a high rigidity with a minimum amount of weight and can be fabricated with a minimum amount of machining, the stiifener rings 15 performing the functions of structural stitleners and acting as radial and axial locators for the stator vane assemblies 3, 11, 13.

In the arrangement shown in Pig. 3 spacer blocks 25 are substituted for the locator beads 17 of the arrangement shown on Fig. 2. The blocks 25 are Welded or otherwise fastened to the stiffener ring 23 which in turn is welded or otherwise secured to the outer casing 1. In the arrangement in Fig. 3 the inner casing or rotor shroud 24 is formed with oflset flanges 26 that are held between the inner ring 13 and the assembly formed by the spacer block 25 and stiffener ring 23.

Fig. 4 shows another arrangement wherein, instead of utilizing a single channel shaped stiffener ring, there is provided for each stage of stator vanes a pair of angle shaped rings 27 having beads 29 formed thereon that act as stiffener rings and also serve to locate the stator vane assembly 3, 11, 13 similar to the stator vane assembly of Figs. 1, 2 and 3. Annular members 31 are secured to the inner diameter of the stiffener rings 27 and are internally ground after assembly to radially I0 cate the stator vane assembly 3, 11, I3 relative to the that cooperate with internally ground spacers 34, secured to the stiffener rings 27, and with members 31 to form a gas seal minimizing leakage between adjacent compres- 'sor stages.

The device shown in Fig. 5 is similar to that of Fig. 4. However, in this arrangement the stifiener rings are formed of two angle members 35 and 36 that are secured together and then secured to the outer casing fl. The outer stiffener ring portion 35 acts to axially align the stator vane assemblies 3, 11, 13 while the inner flange ring 36 acts to radially align the stator vane assemblies. The stiffener ring assembly 35--36 has a ground portion 38 that cooperates with a seal member 33 attached to the rotor blades 5.

A still further'arrangement is shown in Fig. 6 in which the stiffener rings form a combination blade shroud and inner casing. Each channel shaped ring 37 is formed of a single piece, there being provided one channel member 37 between each adjacent stator vane location. The channel member 37 has axially extending flange portions 39 that are welded or otherwise secured to the outer casing 1 and a formed portion 40 that abuts axially extending ground flanges 41 formed on the stator vane ring 43 that cooperate to radially align the parts. The stator ring 43 has beads 45 formed thereon to axially locate the stator vane assembly within the stiffening ring elements 37.

The above described embodiments of the invention are illustrative and are subject to many modifications within the scope of the appended claims.

I claim:

1. An axial flow turbo-machine having an axially extending outer cylindrical casing, a channel shaped stiffener ring having a depth formed by two side portions and a width formed by a connecting bottom portion, said bottom portion being circumferentially secured to the inside of said outer casing, a stator vane assembly including a plurality of vanes secured to a second channel shaped ring of smaller depth and smaller width than the first ring, said second ring being located substantially within said first ring, first means carried by the side portions of one of the rings in engagement with the side portions of said other ring to prevent axial movement but allow radial movement of said second ring and the vanes relative to the first ring and outer casing, and additional means independent of said first means carried by one of said rings in engagement with the other ring to limit outward radial movement but allow axial movement of said second ring and vanes relative to said first ring and outer casing.

2. In an axial flow turbo-machine having a plurality of fluid directing stator stages interposed between a plurality of rotor stages, the combination of an outer cylindrical shell enclosing the stator and rotor stages, a first group of axially spaced outer annular ring members having a channel shaped cross-section and secured to the inside of said outer shell, a second group of axially spaced inner annular ring members each having a channel shaped cross-section and located within the ring members of the first group, a plurality of circumferentially spaced radially extending stator blades carried by each ring member of the second group, continuous surface means carried by each ring member of one of the group engaging continuous surface means on the ring members of the other group to axially align the second group of ring members relative to the first group of ring members, a plurality of cylindrical axially extending inner casing members located between adjacent ring members of each group, means carried by said inner casing members extending between and engaging both the outer ring members and inner ring members, said inner casing and outer ring members forming means radially aligning iaid inner ring members relative to the outer ring memers.

3. In a turbo-machine having at least one set of fluid directing stator vanes, the combination including a cylindrical outer casing, a channel shaped stiffener ring secured to the inner diameter of said casing, a vane carrying channel shaped ring within the stiffener ring and having its open side facing the axis of said turbo-machine, a plurality of circumferentially spaced radially extending vanes extending into and secured to said vane carrying ring, first means carried by one of said rings and engaging the other of said rings to axially align the vane carrying ring relative to said stiffener ring, second means carried by one of said rings cooperating with the other ring to radially align the vane carrying ring relative to said stiffener ring, said second means comprising a first annular, axially extending surface on said stitfener ring and a second cooperating annular axially extending surface on said vane carrying ring, said cooperating surfaces forming the sole means for radial alignment of said vane carrying ring relative to said stiffener ring.

4. In a turbo-machine having at least one set of fluid directing stator vanes, the combination including a cylindrical outer casing, a channel shaped stiffener ring having an axially extending control portion secured to the inner surface of said outer casing and a pair of side portions extending radially inward from said casing, a vane carrying channel shaped ring comprising a central axially extending portion, a pair of side portions extending radially inward and a pair of oppositely directed axially extending flanges at the radially inner end of said side portions, said vane carrying ring having its central portion narrower than the central portion of said stiifener ring and located between the side portions of said stiffener ring, means carried by and protruding from the side portions of one of said rings engaging the side portions of the other ring adapted to axially align the vane carrying ring relative to said stiffener ring and outer casing, a pair of axially extending cylindrical inner casing members on opposite sides of said vane carrying ring, means carried by said inner casing members held between the side portions of said stiffener ring and the axially extending flanges of said vane carrying ring, said inner casing and side portions of said stiffener ring forming means for radially aligning said vane carrying ring relative to said stilfener ring and said outer casing, and a plurality of radially extending, circumferentially spaced vanes extending into said vane carrying ring between the side portions of the same and secured thereto.

References Cited in the file of this patent UNITED STATES PATENTS 2,749,026 Hasbrouck et a1. June 5, 1956 FOREIGN PATENTS 695,724 Great Britain Aug. 19, 1953 

